Heater Heat Conductive Member Segmentation for Uniform Temperature

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Solution Overview

Problem

In image heating apparatuses using electrophotographic systems, non-sheet-passage portion temperature rise causes image defects, thermal expansion issues, and potential damage due to uneven heat distribution and warpage of high heat conductive members, which existing configurations fail to adequately address.

Innovation Solution

The apparatus employs a tubular film with a backup member and an elongated heater, featuring a first heat conductive member with divided sections and a gap, and a second heat conductive member in the gap to ensure uniform heat distribution, with a pinching member to maintain contact and a thermistor and thermal fuse for safety, using a grease with higher thermal conductivity than air to fill the gap and prevent local temperature rises.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a single continuous high heat conductive member is used to equalize temperature distribution, then temperature uniformity is improved, but warpage occurs due to thermal expansion

Engineering Contradiction:

Improvetemperature uniformityVSAvoidstructural stability

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The single continuous high heat conductive member is divided into multiple separate members arranged in the longitudinal direction. This segmentation prevents warpage caused by thermal expansion while maintaining heat conduction through proper arrangement and contact with the heater substrate.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If high heat conductive members are divided and arranged with gaps to prevent warpage, then structural stability is improved, but temperature uniformity deteriorates due to gaps

Engineering Contradiction:

Improvestructural stabilityVSAvoidtemperature uniformity

Core Design Contradiction:

Stability of the object's compositionVSTemperature

Solution Approach 1:

A pinching member is introduced as an intermediary component to press the divided high heat conductive members against the heater substrate. This ensures continuous thermal contact across the gaps, maintaining temperature uniformity while preserving the structural benefits of divided members.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If the heater is brought into contact with the film to heat the toner image, then heating efficiency is improved, but non-sheet-passage portion temperature rise occurs causing image defects

Engineering Contradiction:

Improveheating efficiencyVSAvoidtemperature unevenness

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

Temperature detecting elements and safety elements are positioned to monitor the temperature at the nip portion, providing feedback control that prevents non-sheet-passage portion temperature rise and associated image defects while maintaining efficient heating during normal operation.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration achieves a more uniform temperature distribution across the heater, reducing the risk of image defects and thermal damage, while maintaining the heat equalizing effect of high heat conductive members, effectively preventing hot offset and ensuring satisfactory image quality.

Implementation Method 1

The heat generating resistor, formed on the ceramic heater, inputs a current in a state obtained by subjecting a primary current flowing from an electrical outlet to power control by a control method such as wavenumber control or phase control in a power supply circuit, thereby generating heat and heating an image.

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a high heat conductive member is mounted between the heater substrate and the support member, to thereby obtain a uniform heater temperature distribution in the longitudinal direction

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

using a grease with higher thermal conductivity than air to fill the gap and prevent local temperature rises

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9513586B2Image heating apparatus having film, back-up member forming a nip with the film, a heater, and heat conductive members configured to be brought into contact with heater surface opposite to the surface of the heater brought into contact with the film

Publication Date: 2016.12.06 CANON KK

AI summary

The image heating apparatus includes a tubular shaped film; a backup member configured to be brought into contact with an outer surface of the film; a heater having an elongated shape and being configured to be brought into contact with the film, the heater including a substrate and a heat generating resistor formed; a first heat conductive member having a higher thermal conductivity than the substrate and being configured to be brought into contact with a surface of the heater, the first heat conductive member including divided first heat conductive members arranged with a gap formed therebetween; a pinching member configured to pinch the first heat conductive member; and a second heat conductive member provided in a region of the gap so as to be brought into contact with both of the heater and the pinching member.